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Chem 2425

30 Questions  I  By Ochiengj

  
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1.  What is the correct equilibrium constant expression for the following reaction?         CO2(g) + 2H2O(g)  CH4(g) + 2O2(g) a.                  b.                  c.              d.        
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2.  The initial rates method was used to study the reaction below.         A + 3B =2C     [A] (mol/L)    [B] (mol/L)   -D[A]/Dt (mol/L×s)     0.210        0.150         3.41 x 10^3     0.210        0.300        1.36 x 10^2     0.420        0.300        2.73 x 10^-2
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3.  Calcium carbonate decomposes to calcium oxide and carbon dioxide.   CaCO3(s CaO(s) + CO2(g) ΔH0 = 179 kJ The equilibrium constant for this reaction is 9.7 × 1024 at 298 K. What is the equilibrium constant at 575 K? (R = 8.31 J/mol·K)
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4.  8. All of the following statements are true EXCEPT
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5.  12. The rate of reaction for the formation of carbon monoxide is measured at 1.24 mol/L·hr. What is the rate of formation of carbon monoxide in units of mol/L·s?         CH3CHO(g) → CH4(g) + CO(g)
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6.  5. A coffee-cup calorimeter contains 10.0 g of water at 59.000C. If 3.00 g gold at 15.20 0C is placed in the calorimeter, what is the final temperature of the water in the calorimeter? The specific heat of water is 4.18 J/g ·0C; the specific heat of gold is 0.128 J/g ·0C.
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7.  7. 10.0 g of ice at 0.00 0C is mixed with 25.0 g of water at 35.000C in a coffee-cup calorimeter. What is the final temperature of the mixture? The specific heat of water is 4.18 J/g 0C; the heat of fusion of water is 333 J/g.
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8.  29. Which of the following may change the ratio of products to reactants in an equilibrium mixture for a chemical reaction involving gaseous species?     1.    Increasing the temperature.     2.    Adding a catalyst.     3.    Adding gaseous reactants.
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9.  19. The reaction A → B follows first-order kinetics with a half-life of 21.7 hours. If the concentration of A is 0.023 M after 48.0 hours, what is the initial concentration of A?
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10.  9. Determine the heat of reaction for the combustion of ammonia,         4NH3(g) + 7O2(g) → 4NO2(g) + 6H2O(l) using molar enthalpies of formation. NH3(g)    –45.9 NO2(g)    +33.1 H2O(l)    –285.8
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11.  16. The initial rates method was used to study the reaction below.         2A + B + C → D + E   [A] (mol/L) [B] (mol/L) [C] (mol/L) Δ[D]/Δt (mol/L·s)   0.150 0.250 0.300 1.47 × 106   0.150 0.125 0.300 3.68 × 107   0.150 0.250 0.600 2.94 × 106   0.300 0.125 0.300 7.35 × 107  
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12.  11. For the reaction below relate the rate of disappearance of hydrogen to the rate of formation of ammonia.         N2(g) + 3H2(g) → 2NH3(g)
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13.  25. Write a balanced chemical equation which corresponds to the following equilibrium constant expression.        
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14.  1. If 50.0 g of benzene, C6H6, at 25.00C absorbs 2.71 kJ of energy in the form of heat, what is the final temperature of the benzene? The specific heat of benzene is 1.72 J/g·0C.
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15.  22. For the first-order reaction below, the initial concentration of A is 0.80 M. What is the half-life of the reaction if the concentration of A decreases to 0.10 M in 54 seconds?   A → B rate = k[A]  
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16.  17. The rate constant of a first-order decomposition reaction is 0.0147 s–1. If the initial concentration of reactant is 0.178 M, what is the concentration of reactant after 30.0 seconds?
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17.  3. Water has a specific heat of 4.18 J/g · 0C. If 35.0 g of water at 98.8 0C loses 4.94 kJ of heat, what is the final temperature of the water?
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18.  28. For the system         CO(g) + H2O(g)  CO2(g) + H2(g) K is 1.6 at 900 K. If 0.400 atm CO(g) and 0.400 atm H2O(g) are combined in a sealed flask, what is the equilibrium partial pressure of CO2(g)?
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19.  . Nitrosyl chloride decomposes according to the chemical equation below.         2NOCl(g)  2NO(g) + Cl2(g) A pressure of 0.320 atm of nitrosyl chloride is sealed in a flask and allowed to reach equilibrium. If 22.6% of the NOCl decomposes, what is the equilibrium constant for the reaction?
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20.  18. The rate constant for the decomposition of cyclobutane is 2.08 × 10-2 s-1 at high temperatures.         C4H8(g) → 2C2H4(g) How many seconds are required for an initial concentration of 0.100 M C4H8(g) to decrease to 0.0450 M?
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21.  10. The standard molar enthalpy of formation of NH3(g) is –45.9 kJ/mol. What is the enthalpy change if 9.51 g N2(g) and 1.96 g H2(g) react to produce NH3(g)?
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22.  21. For the second-order reaction below, the rate constant of the reaction is 9.4 × 10–3 M–1s–1. How long (in seconds) is required to decrease the concentration of A from 2.16 M to 0.40 M?   2A → B rate = k[A]2  
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23.  13. For the reaction below, if the rate of appearance of Br2 is 0.180 mol/L·s, what is the rate of disappearance of NOBr?         2NOBr(g) → 2NO(g) + Br2(g)
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24.  Which of the following statements is/are CORRECT?     1.    Product concentrations appear in the numerator of an equilibrium constant expression.     2.    A reaction favors the formation of products if K >> 1.     3.    Stoichiometric coefficients are used as exponents in an equilibrium constant expression.
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25.  20. For the first-order reaction below, the concentration of product B after 24.2 seconds is 0.322 M. If k = 8.75 × 10-2 s-1, what was the initial concentration of A?   A → 2B  rate = k[A]
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26.  14. Dinitrogen pentaoxide decomposes to nitrogen dioxide and oxygen according to the following balanced chemical equation and rate expression.         2N2O5(g) → 4NO2(g) + O2(g)         rate = k[N2O5] What is the overall reaction order?
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27.  6. When 10.0 g KOH is dissolved in 100.0 g of water in a coffee-cup calorimeter, the temperature rises from 25.18 0C to 47.53 0C. What is the enthalpy change per gram of KOH dissolved in the water? Assume that the solution has a specific heat capacity of 4.18 J/g0C.
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28.  2. If 495 J is required to change the temperature of 12.7 g of sodium chloride from 75.00C to 135 0C, what is the specific heat of sodium chloride?
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29.  Use the equilibrium constants for the following reactions at 700 0C   2SO2(g) + O2(g)  2SO3(g) K1 = 4.8   2NO(g) + O2(g)  2NO2(g) K2 = 16 to determine the equilibrium constant for the following reaction.         SO3(g) + NO(g)  SO2(g) + NO2(g)
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30.  4. When 66.0 g of an unknown metal at 28.50C is placed in 83.0 g H2O at 78.50C, the water temperature decreases to 75.90C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g0C.
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